I recommend using an AMD CPU and GPU, but otherwise you can just assume a game works and it will most of the time. If it doesn't, there might be some quick fixes, and if not then it's an unlucky one.

See ProtonDB.

I have big hands so I'd have to go with the Xbox 360 and Xbox One's controller. The DualSense is very good, too. I'd give it to the DualSense for the haptic feedback and vibrations, but they're both great!

For controllers and small devices like this, they could just go with standard AA batteries like Xbox's.

I'm not sure if the manufacturer will be required to make the replacement batteries themselves. For older laptops, you could buy an external battery from a 3rd-party which worked just fine.